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string: Remove strlcpy()

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With all the users of strlcpy() removed[1] from the kernel, remove the
API, self-tests, and other references. Leave mentions in Documentation
(about its deprecation), and in checkpatch.pl (to help migrate host-only
tools/ usage). Long live strscpy().

Link: https://github.com/KSPP/linux/issues/89 [1]
Cc: Azeem Shaikh <azeemshaikh38@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: linux-hardening@vger.kernel.org
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2024-01-18 12:31:55 -08:00
parent e28b035958
commit d26270061a
6 changed files with 1 additions and 80 deletions
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51
include/linux/fortify-string.h
View File

@ -214,51 +214,6 @@ __kernel_size_t __fortify_strlen(const char * const POS p)
return ret;
}
/* Defined after fortified strlen() to reuse it. */
extern size_t __real_strlcpy(char *, const char *, size_t) __RENAME(strlcpy);
/**
* strlcpy - Copy a string into another string buffer
*
* @p: pointer to destination of copy
* @q: pointer to NUL-terminated source string to copy
* @size: maximum number of bytes to write at @p
*
* If strlen(@q) >= @size, the copy of @q will be truncated at
* @size - 1 bytes. @p will always be NUL-terminated.
*
* Do not use this function. While FORTIFY_SOURCE tries to avoid
* over-reads when calculating strlen(@q), it is still possible.
* Prefer strscpy(), though note its different return values for
* detecting truncation.
*
* Returns total number of bytes written to @p, including terminating NUL.
*
*/
__FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, size_t size)
{
const size_t p_size = __member_size(p);
const size_t q_size = __member_size(q);
size_t q_len; /* Full count of source string length. */
size_t len; /* Count of characters going into destination. */
if (p_size == SIZE_MAX && q_size == SIZE_MAX)
return __real_strlcpy(p, q, size);
q_len = strlen(q);
len = (q_len >= size) ? size - 1 : q_len;
if (__builtin_constant_p(size) && __builtin_constant_p(q_len) && size) {
/* Write size is always larger than destination. */
if (len >= p_size)
__write_overflow();
}
if (size) {
if (len >= p_size)
fortify_panic(__func__);
__underlying_memcpy(p, q, len);
p[len] = '\0';
}
return q_len;
}
/* Defined after fortified strnlen() to reuse it. */
extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);
/**
@ -272,12 +227,6 @@ extern ssize_t __real_strscpy(char *, const char *, size_t) __RENAME(strscpy);
* @p buffer. The behavior is undefined if the string buffers overlap. The
* destination @p buffer is always NUL terminated, unless it's zero-sized.
*
* Preferred to strlcpy() since the API doesn't require reading memory
* from the source @q string beyond the specified @size bytes, and since
* the return value is easier to error-check than strlcpy()'s.
* In addition, the implementation is robust to the string changing out
* from underneath it, unlike the current strlcpy() implementation.
*
* Preferred to strncpy() since it always returns a valid string, and
* doesn't unnecessarily force the tail of the destination buffer to be
* zero padded. If padding is desired please use strscpy_pad().

3
include/linux/string.h
View File

@ -66,9 +66,6 @@ extern char * strcpy(char *,const char *);
#ifndef __HAVE_ARCH_STRNCPY
extern char * strncpy(char *,const char *, __kernel_size_t);
#endif
#ifndef __HAVE_ARCH_STRLCPY
size_t strlcpy(char *, const char *, size_t);
#endif
#ifndef __HAVE_ARCH_STRSCPY
ssize_t strscpy(char *, const char *, size_t);
#endif

2
lib/nlattr.c
View File

@ -758,7 +758,7 @@ EXPORT_SYMBOL(nla_find);
* @dstsize: Size of destination buffer.
*
* Copies at most dstsize - 1 bytes into the destination buffer.
* Unlike strlcpy the destination buffer is always padded out.
* Unlike strscpy() the destination buffer is always padded out.
*
* Return:
* * srclen - Returns @nla length (not including the trailing %NUL).

15
lib/string.c
View File

@ -103,21 +103,6 @@ char *strncpy(char *dest, const char *src, size_t count)
EXPORT_SYMBOL(strncpy);
#endif
#ifndef __HAVE_ARCH_STRLCPY
size_t strlcpy(char *dest, const char *src, size_t size)
{
size_t ret = strlen(src);
if (size) {
size_t len = (ret >= size) ? size - 1 : ret;
__builtin_memcpy(dest, src, len);
dest[len] = '\0';
}
return ret;
}
EXPORT_SYMBOL(strlcpy);
#endif
#ifndef __HAVE_ARCH_STRSCPY
ssize_t strscpy(char *dest, const char *src, size_t count)
{

5
lib/test_fortify/write_overflow-strlcpy-src.c
View File

@ -1,5 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-only
#define TEST \
strlcpy(small, large_src, sizeof(small) + 1)
#include "test_fortify.h"

5
lib/test_fortify/write_overflow-strlcpy.c
View File

@ -1,5 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-only
#define TEST \
strlcpy(instance.buf, large_src, sizeof(instance.buf) + 1)
#include "test_fortify.h"